The invention pertains to fire alarm systems. More particularly, the invention pertains to testable flow detection systems wherein the presence of flow is often indicative of an alarm or fire condition.
One form of known fire alarm system includes waterflow conduits or pipes which are coupled to sprinkler heads. The sprinkler heads contain a heat sensitive material. In the presence of elevated temperature, such as caused by a fire, the material in the sprinkler heads melts and water, under pressure in the pipes or conduits, sprays from the sprinkler heads to suppress the fire in the adjacent area.
It is also known to incorporate flow detectors into the conduits of such suppression systems. Examples of such flow detectors can be found in Merchant U.S. Pat. No. 4,782,333 as well as Griess U.S. Pat. No. 4,791,414, both of which are assigned to the assignee hereof. Such flow detectors conventionally include a sensor which extends into the respective pipe or conduit and which is moved from a quiescent position to an active position in response to a waterflow in the pipe or conduit. This movement produces an output signal indicative of the flow of water which is also associated with the presence of a fire condition.
A problem has been recognized with respect to such flow detectors in that they usually remain in a quiescent state for long periods of time due to the absence of an alarm or fire condition. However, such detectors are expected to function properly in the presence of flow, which is of course indicative of the presence of a fire or an alarm condition, notwithstanding long intervals which could be months or years without any fire conditions.
It would be desirable therefore to be able to provide a test system for flow detectors which could be used to conduct a variety of different tests of the respective detector on a routine basis and in the absence of an emergency or fire condition. Preferably, it would be possible to interconnect the units for a plurality of detectors such that groups of detectors could be tested at essentially the same time.
A test unit for a fluid flow detector includes a programmed processor which executes a set of preloaded instructions for carrying out one or more tests of an associate flow detector. An auxiliary water pump can be used to provide a flow of test fluid to actuate the detector. Output drive circuitry is coupled between the programmed processor and the pump such that the pump operates under the control of the programmed processor. Output drive circuitry can be implemented using relays or solid state drive circuits.
An input port of the processor can be coupled to the signal output port from the respective detector. The processor can include a second input port, for example from another identical test unit, when the test units are grouped together with a group of flow detectors. The test units can also include a manually operable control element, such as a multi-position key switch or keyboard for purposes of carrying out locally controlled tests.
In one instance, the executable instructions in the processor, in connection with a timer or a real time clock included in the processor, can activate the output circuitry periodically, for example every several days, for a brief period of time, on the order of 300 milliseconds, for purposes of minimizing pump impeller junk or crud buildup. In another mode, the processor can activate the circuitry continuously to conduct a test of the respective detector.
In a group test mode, placing one of the test units in the group test mode transmits a signal to each of the other units in the group whereupon all of the units in the group energize their respective water pumps and sense test indicating signals from the respective detectors substantially at the same time. Alternately, the units can function sequentially with each member of the group carrying out its test sequence depending upon its position in the group.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.